The effects should work without any footswitch connected. If you look at the back panel of the chassis, there should be a metal tag with the model number stamped on. Something like K250-2. If you tell us exactly which amp you have we can point you to the schematics in the technical section of the site.
If the connectors for the pc board have been cleaned and the solder joints have been checked, there may be an electronic problem with the circuit. If you have the skills, we can help you fix it or help the person that fixes for you.